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Summary The purpose of our study was to determine the types of lesions that cause colic in juvenile Thoroughbreds, factors associated with these lesions and the subsequent survival and athletic performance of the juveniles. The age of juvenile Thoroughbreds requiring surgical exploration for abdominal pain has an influence on the type of lesion causing colic. The short-term survival rate (discharge from the hospital) after colic surgery for foals was 85% and was strongly influenced by the lesion causing colic. Thirteen percent of juveniles recovered from the first surgery experienced another severe colic episode requiring additional surgery or euthanasia. Eight percent of foals recovered from the first celiotomy developed adhesions. Adhesion formation was related to the initial lesion causing colic and the foals' age at the first surgery. Foals being suckled (15 days to 6 months) were at greatest risk for adhesions and more frequently required multiple surgeries. Juvenile Thoroughbreds that had a celiotomy were significantly less able to race (63%) than their unaffected siblings (82%), and age at the initial surgery was associated with the percentage of horses that raced. However, affected foals able to race won as much money, raced as often, and made as many starts as their siblings. Colic and surgical treatment have a negative impact on athletic performance, but the majority of foals discharged from the hospital after colic surgery will perform athletically as adults.

By use of wire ropes as the transosseous component, an external skeletal fixator for the repair of long bone fractures in horses and cattle has been designed and tested in axial compression. Theoretical methods were used in the design process to size fixator components; however, our results suggest that conventional methods of analyzing the displacement of the transosseous component may not apply to wire ropes. Large pretensions in the wire ropes are necessary to obtain functional stiffnesses for fracture fixation. Therefore, a method was sought for terminating the ropes so that an appropriate pretension could be introduced into the rope through its interface with the fixator rings. Ropes were terminated by use of 5 methods and were tested in axial tension to failure. These methods included 3 copper sleeve arrangements, welded ends, and drum sockets. The drum sockets (57.6% of rope breaking strength) far exceeded the strengths provided by the copper sleeves (8.5 to 26.6%) and the welded ends (44.3%). Using the drum sockets, 5 rope configurations were assembled to the fixator, using wood blocks to simulate bones with a gap defect. The fixator was loaded in axial compression for each of the rope configurations, and stiffnesses were determined from measured axial displacement and applied load. The 4-ring fixator configuration, with 2 ropes at 60 degrees angular separation/ring, was the stiffest. In a worst case (gap) model, a mean axial compression load of 1,730 N was observed at 2 mm of displacement for a 4-ring fixator configuration.(ABSTRACT TRUNCATED AT 250 WORDS)

We evaluated the single-cycle structural properties for axial compression, torsion, and 4-point bending with a central load applied to the caudal or lateral surface of a diaphyseal segment from the normal adult equine humerus, radius, third metacarpal bone, femur, tibia, and third metatarsal bone. Stiffness values were determined from load-deformation curves for each bone and test mode. Compressive stiffness ranged from a low of 2,690 N/mm for the humerus to a high of 5,670 N/mm for the femur. Torsional stiffness ranged from 558 N.m/rad for the third metacarpal bone to 2,080 N.m/rad for the femur. Nondestructive 4-point bending stiffness ranged from 3,540 N.m/rad for the radius to 11,500 N.m/rad for the third metatarsal bone. For the humerus, radius, and tibia, there was no significant difference in stiffness between having the central load applied to the caudal or lateral surface. For the third metacarpal and metatarsal bones, stiffness was significantly (P0.05) greater with the central load applied to the lateral surface than the palmar or plantar surface. For the femur, bones were significantly (P0.05) stiffer with the central load applied to the caudal surface than the lateral surface. Four-point bending to failure load-deformation curves had a bilinear pattern in some instances, consisting of a linear region at lower bending moments that corresponded to stiffness values from the nondestructive tests and a second linear region at higher bending moments that had greater stiffness values.(ABSTRACT TRUNCATED AT 250 WORDS)

As more sophisticated research is performed to refine fracture fixation techniques for horses, it is important that normal values for the geometric properties of the bones of the appendicular skeleton be determined and that suitable controls be available. We evaluated the geometric properties of total bone width, cortical bone width, and medullary canal/trabecular bone width measured from 2 radiographic projections of equine long bones (humerus, radius, third metacarpal bone, femur, tibia, and third metatarsal bone) obtained from a general population of horses. Measurements were performed on slices separated by intervals equal to 5% of the bone's length. Slices were then grouped into 5 regions: proximal epiphysis, proximal part of the metaphysis, diaphysis, distal part of the metaphysis, and distal epiphysis. Results validated use of the contralateral bone as a control for assessing experimental models or clinical cases. Of 858 homotypic slice comparisons between left and right bones, significant (Por = 0.05) differences were detected in 31 (3.6%) of the comparisons. Of 168 homotypic region comparisons, significant differences were observed in 3 (1.8%) of the comparisons. The greatest variation between left and right bones was observed in metaphyseal regions, areas with bony protuberances, and regions with prominent bone superimposition. At a power of 0.8 for the statistical tests performed in this study, the mean homotypic variation of bones in each region is5.8% for the proximal epiphysis, 11.3% for the proximal part of the metaphysis, 6.8% for the diaphysis, 12.2% for the distal part of the metaphysis, and 5.2% for the distal epiphysis.

A 5-year-old Quarter Horse mare was examined because of a 6-month history of quidding and nasal discharge that contained feed material. Physical examination revealed weight loss and dorsal displacement of the soft palate, caused by a soft tissue mass located at the dorsal aspect of the base of the tongue. Surgical resection of the mass was successfully performed through an oral approach. The histopathologic diagnosis was rhabdomyosarcoma.

A modification of the Roux-en-Y anastomosis procedure was used to bypass a pyloroduodenal mass in a 12-year-old Arabian stallion. Clinical signs had consisted of a 4-week progression of ventral and hind limb edema, hypoproteinemia, fecal occult blood, intermittent abdominal pain, weight loss, and gastric reflux. On exploratory celiotomy, an obstructive mass was found in the pylorus and proximal portion of the duodenum. Gastrojejunostomy and duodenojejunostomy were performed by use of stapled side-to-side anastomosis techniques. Inaccessibility of the obstructed pyloric region prevented resection of the affected area.

Incarceration of the large colon through a rent in the gastrosplenic ligament of a horse was surgically corrected via ventral midline celiotomy. Clinical signs were similar to those in other horses with nonstrangulating large colon disorders. Diagnosis of large colon incarceration in the gastrosplenic ligament was determined by surgical abdominal exploration. The findings of medial deviation of the spleen, location of the large colon lateral to the stomach and caudolateral to the spleen, and caudocraniad passage of the large colon through the gastrosplenic ligament are similar to findings in horses with small intestinal incarcerations in the gastrosplenic ligament. Correction was facilitated by performing a pelvic flexure colotomy and evacuating colonic contents prior to returning the large colon through the rent to its normal anatomic position.

The third carpal bone (C3) was collected from both forelimbs of 27 Thoroughbreds. On the basis of age, training, and history, specimens were assigned to 1 of 5 groups: yearling, untrained horses (group 1, n = 4); 2- to 3-year-old, untrained horses (group 2, n = 7); trained 2-year-old horses (group 3, n = 6); trained 3-year-old horses (group 4, n = 6); and 3-year-old, trained horses with carpal pathologic features (group 5, n = 4). A transverse section of subchondral bone 5-mm thick was cut in a precise fashion 10 mm below the proximal articular surface of all specimens. After high-detail radiography was done, indentation testing was performed on the proximal surface of the section at points 5 mm apart. The stiffness of the subchondral cancellous bone was determined from the slope of the load vs displacement curve. Topographic plots of stiffness measurements were compared with radiographs of each specimen. Point determinations were averaged to derive measures for the radial and intermediate facets, and for regions 5, 10, 15, and 20 mm from the dorsal margin of C3. Area fraction (1-p; p = porosity) was measured for the radial and intermediate facets, using an automated image analysis system. Significant (P less than 0.05) increases in stiffness and area fraction were found in the C3 from trained horses (groups 3 to 5), compared with untrained horses (groups 1 to 2). Stiffness and area fraction of the radial facet of pathologic C3 were significantly higher than the same variables measured in C3 from any other group.(ABSTRACT TRUNCATED AT 250 WORDS)

A randomised, blind prospective study was performed to evaluate effects of low dose heparin therapy on complication and survival rates in 33 horses following exploratory celiotomy. Four horses had non-strangulating lesions and seven had strangulating lesions of the small intestine, 19 had non-strangulating lesions of the large intestine, and three had duodenitis-proximal jejunitis. Eighteen required an enterotomy or intestinal resection and anastomosis. Sixteen received heparin subcutaneously (66 iu/kg every 12 h) post operatively and 17 received a saline placebo for a mean of 3.7 days. There was a significant (P < 0.01) mean decrease in PCV (29.1 per cent) in the heparin group. No significant differences in complication or survival rates were seen between groups. Long term follow-up was obtained for 10 horses in each group. There were no significant differences between groups.

The stiffness, load to failure, and bending moments of adult intact equine humeri and humeri repaired with 3 fixation techniques were determined in vitro. Bones were tested in axial compression (30 pairs), mediolateral 3-point bending (15 pairs), and caudocranial 3-point bending (15 pairs). An oblique osteotomy of 1 humerus of each pair was performed to simulate the long spiral oblique fractures that occur clinically in horses. Bones were repaired in 3 ways: group 1--nylon band cerclage fixation (20 bones); group 2--multiple intramedullary pinning (20 bones); and group 3--nylon band cerclage fixation and multiple intramedullary pinning (20 bones). Intact bones were significantly (P less than 0.05) stronger than repaired bones in each testing mode. Bones repaired with bands only were significantly less stiff in bending than were bones repaired with pins only or with pins and bands. In compression, only specimens repaired with pins and bands were significantly stiffer than were bones repaired with bands only. Bones repaired with bands only required significantly less load to failure in compression and in caudocranial bending than did bones repaired with pins only or with pins and bands. Bones repaired with pins only deformed through the full displacement of the actuator (5 cm), and pins deformed plastically. Bones repaired with pins and bands were stiffer and had higher bending moments than did bones repaired with pins only, but the differences were not significant.

The medical records of 10 horses with invasive neoplasms of the penis, prepuce, and/or superficial inguinal lymph nodes in which treatment involved en bloc resection and penile retroversion were reviewed. All were geldings and ranged in age from 12 to 25 years (mean, 19 years). Evaluation of biopsy specimens obtained before surgery confirmed lymphosarcoma in 1 horse and squamous cell carcinoma in 9 horses. Typical history included swelling, ulceration, and abscessation of the penis and prepuce and large superficial inguinal lymph nodes. Complications after surgery included dehiscence of the urethrostomy site (4 horses), dehiscence of the ventral skin incision (1 horse), urine scalding of 1 hind limb (1 horse), cystitis (1 horse), severe hemorrhage (1 horse), and diarrhea (1 horse). One horse was euthanatized during hospitalization, because of severe dehydration secondary to diarrhea. At necropsy, firm nodules were scattered in the pulmonary parenchyma, myocardium, thyroid gland, parathyroid glands, cranial mediastinum, kidneys, and hilar lymph nodes. Microscopic examination of the nodules revealed undifferentiated carcinoma. Nine horses were discharged from the hospital between 1 and 5 weeks after surgery. The mean follow-up interval was 27 months (range, 6 to 96 months). Eight horses had no evidence of recurrence. One horse had recurrence of neoplasm at 6 months and was euthanatized 12 months later.

Multiple myeloma was diagnosed in a 22-year-old Arabian mare with a history of chronic weight loss. Quantitative immunoglobulin analysis revealed monoclonal gammopathy (IgG(T), 9,800 mg/dl). Due to progressive weight loss, the horse was euthanatized. Microscopy of tissues revealed plasma cell infiltrates in bone marrow, spleen, pituitary gland, adrenal cortex, muscle of the tongue, and bronchial, renal, and mesenteric lymph nodes.

In a retrospective study, we examined the case records for 69 horses with noncomminuted fractures of the proximal phalanx, excluding proximal chip fractures. Forty-nine of the horses sustained the fracture while racing or training for racing. Radiographic examination of all affected limbs was performed, and fractures were classified into 6 noncomminuted types: midsagittal fractures, including short incomplete midsagittal fractures, long incomplete midsagittal (LIMS) fractures, and complete midsagittal (CMS) fractures; dorsal frontal fractures; distal joint fractures; plantar process fractures; physeal fractures; and oblique fractures. Four horses were destroyed before treatment. Sixty-five horses were treated and 63 survived to go home. Long-term follow-up evaluation of the horses that were sent home revealed that 4 were euthanatized after discharge because of persistent lameness of the fractured limb. Of the 59 remaining horses, 34 returned to racing, 7 were used as show or pleasure riding animals, 8 were used for breeding, and 10 were lost to follow-up. More Standardbreds with noncomminuted proximal phalangeal fractures returned to racing than did Thoroughbreds. Of 30 Standardbreds that raced or trained before the fracture, 23 (76.7%) returned to racing--8 to their previous level of performance, 11 to a lower level of performance, and 4 to an unknown level of performance. The Standardbreds that returned to racing were horses with physeal fractures (2/2), LIMS fractures (4/4), CMS fractures (11/16), short incomplete midsagittal fractures (4/7), distal joint fractures (1/2), and plantar process fractures (1/2). Of 21 Thoroughbreds that raced or trained before the injury, 11 (52.4%) returned to racing--7 to their previous level of performance and 4 to a lower level of performance.(ABSTRACT TRUNCATED AT 250 WORDS)

A 3-month-old Quarter Horse filly stepped on a fence staple and developed navicular bone osteomyelitis of the right hindfoot. A 1.5-cm spherical portion of medullary cavity containing purulent material was debrided and flushed with 0.9% NaCl solution. Cancellous bone was collected from a caudal sternebra and placed into the defect. The solar defect had filled with granulation tissue and was epithelialized 6 weeks after surgery. At 6-month follow-up evaluation, the navicular bone defect had healed and the foal was sound on the limb. Cancellous bone grafting may have merit for the treatment of navicular bone osteomyelitis in the horse.

The medical records of 13 horses with strangulated umbilical hernias were reviewed. Typical history included increased swelling, warmth, and firmness of the hernial sac. Enterocutaneous fistulas had developed in 2 horses. Four horses had signs of abdominal pain. Surgery was performed on all horses, and the hernia was reduced by an open reduction technique. Incarcerated tissue included omentum (1 horse), jejunum (5), ileum (4), cecum (1), and ventral colon (2). All horses survived and were discharged from the hospital. Follow-up information on 9 horses (5 to 52 months after discharge) revealed no complications in 6 horses. Of the remaining 3 horses, one horse was euthanatized 5 months after discharge because of laminitis. One horse had persistent drainage from the skin incision requiring removal of nonabsorbable suture material 8 months after discharge. One foal required a second surgery because of signs of abdominal pain 17 days after the initial surgery. The foal was euthanatized during surgery because of severe peritonitis secondary to anastomotic leakage.

Nuclear scintigraphy was used to evaluate healing of third metacarpal bone (MC III) fractures in 2 horses (horses 1 and 2) and a third metatarsal bone fracture in 1 horse (horse 3) after stabilization of each fracture with 2 broad dynamic compression plates. In horse 1, the fracture had uniform uptake of 99mTc methylene diphosphonate on days 1, 15, and 30 after surgery. The fracture healed, and the horse was discharged from the clinic on day 52. In horse 2, a 6-cm photopenic region (ie, area of low radioactivity) was seen over the diaphysis of MC III on day 3. The region persisted and became more distinct by day 32. The diaphysis of MC III sequestered, and horse 2 was euthanatized on day 44. In horse 3, vascularity was seen bridging the fracture on day 5, with a 3-cm photopenic region over the dorsal diaphysis of the third metatarsal bone. By days 18 and 32, uptake of 99mTc methylene diphosphonate in the region had increased, indicating vascularization of the site. the fracture healed, and horse 3 was discharged from the clinic on day 47. Our findings indicated that serial nuclear scintigraphy can be used to evaluate fracture vascularization after surgery in horses.

Nine Thoroughbred racehorses were admitted with cellulitis (of one or more limbs) associated with coagulase-positive staphylococci. The right hindlimb was affected in 4 horses, the right forelimb in 2, the left hindlimb in 1, and both hindlimbs in 2. Typical abnormalities included high values for rectal temperature (9 horses) and heart rate (5 horses), hyperfibrinogenemia (7 horses), leukocytosis (7 horses), and neutrophilia (6 horses). The staphylococcal isolants were speciated in 3 horses and classified as Staphylococcus aureus. Complications included skin loss (5 horses), laminitis of the affected limb (2 horses), laminitis of the contralateral limb (4 horses), osteomyelitis and sequestrum formation (2 horses), and bacteremia (1 horse). Five horses were euthanatized because of the severity of the complications, ie, laminitis in 4 horses and severe skin loss in 1 horse. The remaining 4 horses were discharged from the clinic. At follow-up evaluation (mean, 16.7 months), the swelling in 3 of the horses had completely resolved. One horse returned to racing; of 2 used for pleasure riding, one was mildly lame. The remaining horse was not lame, but was used for breeding because of persistent swelling of the affected limb.

Four horses operated on for left dorsal displacement of the large colon (LDDLC) had major intraoperative or postoperative complications. One horse was euthanatized during surgery because of extensive necrosis of the large colon. Three horses that were discharged after surgical correction of LDDLC were readmitted with signs of abdominal pain between 5 weeks and 13 months after surgery. Two horses had recurrence of LDDLC, and the third horse had an omental adhesion attached to and obstructing the pelvic flexure. The displacements were corrected, the adhesion was broken down, and the horses were discharged. One horse was readmitted a third time 16 months after the second surgery and required a third surgical correction of LDDLC.

Over a 4-year period, vertebral body abscess was diagnosed in 5 young cattle. The laboratory findings in most of these cases did not suggest a diagnosis of vertebral body abscess. The most important basis for diagnosis of this condition was a thorough neurologic examination. In 4 cases, necropsy revealed abscesses in the lungs or thoracic cavity as well, suggesting that a history of pneumonia preceding paresis may favor the diagnosis of vertebral body abscess.

A study was designed to evaluate 2 colopexy techniques (A and B) in 8 clinically normal horses to determine which technique would prevent recurrence of large-colon displacement and/or volvulus. For technique A, 35 cm of the lateral free band of the left ventral colon was sutured to the abdominal wall, 6 cm to the left of ventral midline. For technique B, the medial free band of the left ventral colon was sutured to the medial free band of the right ventral colon, and 8 cm of the lateral free band of the left ventral colon was sutured to the abdominal wall, 6 cm to the left of ventral midline. One horse from each group was euthanatized at 6 months, and another at 12 months after surgery. The position of the large colon, the integrity of the colopexy, and other adhesions within the abdominal cavity were evaluated. At necropsy, attempts were made to manually create displacement and volvulus of the large colon. The remaining horses in each group were anesthetized 6 months or 12 months after surgery, and the integrity of the colopexy was evaluated. After a 60-day recovery period, these horses were exercised for 2 months. Although each horse initially lost weight, the weight of all but 2 was acceptable at the conclusion of the study. Two horses that had technique-B colopexies had progressive weight loss serious enough to warrant euthanasia. Both colopexy techniques prevented manual creation of large-colon displacement and large-colon volvulus centered at the sternal and diaphragmatic flexures. Technique-A colopexy also prevented manual creation of volvulus of the large colon centered at its base.(ABSTRACT TRUNCATED AT 250 WORDS)

Three adult horses were admitted with chronic coronary band avulsions of 2-, 3-, and 46-month durations, respectively. The hoof had a typical appearance in all 3 horses, with a spur of coronary band and associated horn growing at right angles to the hoof wall. Each horse was anesthetized, and the coronary band was reconstructed. Follow-up evaluation of the 3 horses (12, 15, and 23 months after surgery, respectively), revealed healing of all 3 avulsed coronary bands. Mild roughening of the hoof wall distal to the previous avulsion site was observed.